Supply of cold water to the low-pressure side of hot water pumps



March 31, 1964' H. VOGLER 3,126,875

SUPPLY OF COLD WATER TO THE LOW-PRESSURE SIDE OF HOT WATER PUMPS FiledAug. 16, 1960 2 Sheets-Sheet 1 Jnvenlor:

Hons Vogler BY ATTORNEYS March 31, 1964 I H. VOGLER 3,126,875

SUPPLY OF COLD WATER TO THE LOW-PRESSURE SIDE OF HOT WATER PUMPS FiledAug. 16, 1960 2 Sheets-Sheet 2 Jnvenfor:

Hons Vogler BY P MWE-XW (f tn ATTORNEYS United States Patent Thisinvention relates to a device for supplying cold water to thelow-pressure or suction side of pumps in hot water systems having acontrol valve for the cold water feed.

The injection of cold water on the suction side of hot water pumpingsystems is a known procedure for eliminating the risk of waterevaporation in the pump due to pressure drops or similar disturbances.When using this known procedure, the cold water feed is controlled by acontrol valve included on the suction side of the pump that isresponsive to both the temperature and the pressure of the hot waterbeing circulated by the pump. However, this arrangement is cumbersomesince a reference pressure must be maintained at all times.

By contrast, my novel system provides for the control valve for the coldwater feed to be responsive to impulses derived from transient pressurevariations or rate of pressure variations occurring on the suction sideof the pump. My new system is simpler than the conventional systems inthat it is controlled as a function of but one operating variable. Theoperating temperature variable need not be determined since whateverdisturbances may occur are due only to rapid pressure drops. Moreover,my new system permits greater freedom in selecting the point where thepressure variation determining the impulse actuating the control valvemay be positioned than when the conventional system is used, where theconnecting point for the temperature-sensitive element, and consequentlyfor the control valve, must be accurately positioned.

Referring to the drawings which illustrate two preferred embodiments ofmy invention,

FIG. 1 illustrates diagrammatically a hot water pumping systemincorporating a cold water feed control valve responsive to rate ofpressure variations occurring on the suction of the pump; and,

FIG. 2 illustrates diagrammatically a slightly different embodiment thanthat shown in FIG. 1 wherein the control valve is also responsive toload of a steam generator.

Referring to the drawings wherein similar parts have the same referencenumeral, and in particular to FIG. 1, the numeral 1 denotes a hot Watertank, and 2 a hot water feed line connecting hot water tank 1 with thesuction side of pump 3. Hot water is stored in hot water tank 1 understeam pressure, and condensate is delivered to it through a line 10.

In addition to line 2, a line 11 is connected to tank 1 and leads to apressure-differential measuring device 4 comprising a diaphragm 12. Aline 13 branches off line 11 ahead of the point Where line 11 passesinto the casing of the pressure-diiferential measuring device 4. Line 13has therein a throttling member 7 and the line discharges into a vessel,designated by V, of any desired shape and having a considerably largervolume than the chamber of the device 4 into which line 11 passes andthe section of line 11 between line 13 and the casing of the device 4. Aline 14 leads from vessel V to the casing of pressurediiferentialmeasuring device 4, passing, however, into a chamber that is separatedby diaphragm 12 from the chamber into which line 11 passes.

A valve stem 15 is attached to diaphragm 12 and forms part of a controlvalve 5 in a cold water feed line 16 through which cold Water issupplied to the system. Downstream from control valve 5 in the directionof flow of the cold water, line 16 is divided into four parallelbranches 6, in each of which a controllable branch throttling element 8is provided. Branches 6 discharge into the hot water feed line 2 betweentank 1 and pump 3.

The principle of operation of the system according to FIG. 1 is asfollows: Normally, pump 3 draws hot water from tank 1 through line 2 anddelivers it in the direction of arrow 17to a steam generator, forexample. When the pressure in tank 1 drops with attendant danger ofevaporation of the water in pump 3, control valve 5 is opened by meansof pressure-differential measuring device 4, and cold water flowsthrough cold water feed line 16 and its branches 6 into the hot waterfeed line 2.

The opening of control valve 5 is brought about by the fact that in thecase of a pressure drop on the suction side of the pump, the pressure onthe right-hand side (in FIG. 1) of diaphragm 12 drops more rapidly thanon the left-hand side of the diaphragm since, due to throttling member 7and vessel V, the relatively high pressure on the left-hand side of thediaphragm is maintained for a short period of time. Pressure will thendrop gradually in the chamber on the left-hand side of the diaphragmuntil it is equal to that in the chamber on the right-hand side of thediaphragm. The sensitivity of pressure-differential measuring device 4,and with it the sensitivity of its responsive action upon control valve5, may be varied by adjustment of throttling member 7. Controllablebranch throttling elements 8 in branches 6 permit the distribution ofthe cold water over the length of hot water feed line 2 to be variedwith respect to location and quantity.

Referring to FIG. 2, it is seen that the embodiment shown in FIG. 1 ismodified in that throttling elements 7 and 8' are controlled as afunction of the load of a steam generator (not shown). For this purpose,a control box 18 is provided in which a shaft 19 is supported. The leftend of shaft 19 (in FIG. 2) projects from the box and is linked througha lever 20 and a rod 21 to a load-control device (not shown) of thesteam generator. Four disk cams 22 are mounted on shaft 19 and alongwith rollers 25 and push rods 23 control the associated throttlingelements 8'.

There is further mounted on shaft 19, a disk cam 24 which acts through aroller 26 on a push rod 27 and through a bell crank 28, upon throttlingelement 7' in line 13. In addition, shaft 19 carries a disk cam 30which, through a roller 32 on a push rod 31 and through a bell crank 33,actuates a member 34 controlling the pressure of the cold water. Member34 comprises a cylinder 35 which connects through a pipe 36 to coldwater feed line 16. A piston 37 slides in cylinder 35 with its rod 38being attached to one end of a two-armed lever 39. Piston rod 38 passesthrough a bushing 40 which on one side is positively connected to bellcrank 33 and on the other side abuts on a spring 41 which in turn bearson piston 37. The other end of lever 39, pivoted at 42, is linkedthrough a rod 43 with a valve 44 in the cold water feed line which islocated upstream in the direction of flow of the cold water of pipe 36.

Member 34, along with valve 44, permits variation of the cold waterpressure ahead of control valve 5, and therefore allows variation of thequantity of cold water to be fed to the hot water pumping system to be afunction of the load of the steam generator. This regulation of coldwater feed is in addition to that regulation by control valve 5.

By proper design of the disk cams 22, 24 and 30 it is possible to fixwith cams 22 the location and quantity of the individual injectionsthrough the branches 6, to fix with cam 30 the cold water pressureupstream of valve 5 and hence the entire quantity injected, and with cam24 to fix the stroke of the valve stem 15, all for specified loads ofthe steam generator. Forexample, disk earns 22 may be designed so thatat 30 percent steam-generator load only the upper two branch pipes 6will inject water while throttling elements 8' of the lower two branchesare closed; and the quantity of water to be injected through the uppertwo branch pipes may further ditfer as between the two branches. At 60percent load, for example, water may be injected through three or allfour branch pipes; and in this case also, the quantity of water injectedthrough the individual branch pipes may be graduated as desired.

While there have been illustrated and described two embodiments of myinvention, no limitations are necessarily made to the precise detailsshown and changes and modifications falling within the scope of theappended claims may be resorted to without departing from the spirit orscope of this invention.

I claim:

1. Apparatus for the supply of hot water comprising a hot water feedline, a pump connected at its low pressure side to said feed line, acold water feed line connecting into said hot water feed line upstreamof said pump, a valve in said cold water feed line, means to measure thetime rate of drop of pressure in said hot water feed line, and means tovary the opening of said valve directly with said time rate of drop ofpressure.

2. Apparatus according to claim 1 wherein said means for measuring timerate of drop of pressure comprise a chamber, a diaphragm dividing theinterior of said chamber into two portions, and unlike conduitsconnecting the interior of said chamber on opposite sides of saiddiaphragm to the low pressure side of said pump, and wherein said meansto vary the opening of said valve comprise means coupling said diaphragmto said valve.

3. Apparatus according to claim 1 wherein said means for measuring timerate of drop of pressure comprise a chamber, a diaphragm dividing theinterior of said chamber into two portions, and conduits of unlikevolume connecting the interior of said chamber on opposite sides or"said diaphragm to the low pressure side of said pump,

and wherein said means to vary the opening of said valve comprise meanscoupling said diaphragm to said valve.

4. Apparatus according to claim 2 wherein one of said conduits includesa throttling device.

5. Apparatus according to claim 4 wherein said cold water feed lineincludes downstream of said valve a plurality of branches connectinginto said hot water feed line at distinct points adjacent said pump, anda separate throttling device in each of said branches.

6. Apparatus according to claim 5 in which the outlet of said pump leadsto a steam generator, said apparatus further including steam generatorload responsive means coupled to each of said throttling devices.

7. Apparatus according to claim 6 further including a throttling devicein said cold water feed line upstream of said valve, and means couplingsaid last-named throttling device to said steam generator loadresponsive means.

8. Apparatus for the supply of hot water comprising a hot water tank, apump for pumping hot water from said tank to a point of use, a hot Waterfeed line leading from said tank to the low pressure side of said pump,a cold water feed line communicating with said hot water feed line, avalve in said cold water feed line, means to measure the time rate ofdrop of pressure in said tank, and means to vary the opening of saidvalve directly with said time rate of drop of pressure.

9. Apparatus according to claim 8 wherein said means to measure the timerate of pressure drop comprise a chamber having a diaphragm therein, aconduit connecting said chamber on one side of said diaphragm with saidtank, and a branch conduit connecting said first-named conduit with thesaid chamber on the other side of said diaphragm, the volume of saidbranch conduit being unequal to the volume of said first conduit betweensaid branch conduit and said chamber.

References Cited in the file of this patent UNITED STATES PATENTS2,489,345 Welch Nov. 29, 1949 FOREIGN PATENTS 1,070,497 GermanyDecT5,l9S9

8. APPARATUS FOR THE SUPPLY OF HOT WATER COMPRISING A HOT WATER TANK, APUMP FOR PUMPING HOT WATER FROM SAID TANK TO A POINT OF USE, A HOT WATERFEED LINE LEADING FROM SAID TANK TO THE LOW PRESSURE SIDE OF SAID PUMP,A COLD WATER FEED LINE COMMUNICATING WITH SAID HOT WATER FEED LINE, AVALVE IN SAID COLD WATER FEED LINE, MEANS TO MEASURE THE TIME RATE OFDROP OF PRESSURE IN SAID TANK, AND MEANS TO VARY THE OPENING OF SAIDVALVE DIRECTLY WITH SAID TIME RATE OF DROP OF PRESSURE.